Hey all swap guys, you all need this!
Fiero C203 & C500
This is a list of all the connections that are needed to tie into the Fiero electrical system when doing an engine conversion. This list is to aide in the wiring process. All circuits should be verified before any connections are made. To the best of my knowledge, all of the info below is correct.
The C203 connector is clear plastic and located under the center console. The C500 connector is next to the battery, half of it is for the tail light harness, the other half for the engine. Descriptions of each one follows:
Fiero C203 connector
Pos. Wire color Circuit Description
A Tan/Black Upshift lamp Grounding this wire will make the upshift indicator come on.
B Orange Fuel Pump Positive feed for the fuel pump relay. Hot at all times fused 10A
C Brown/White SES lamp Grounding this wire will make the "Service Engine Soon" indicator come on
D Lt Blue A/C on Positive feed for the A/C compressor control relay coil. Hot when A/C is on.
E Tan Oil gage Connect to oil pressure sender, 90 ohms at max pressure
F Pink/Black ECM Ign. Positive feed for ECM. Hot in run, bulb test, or start. fused 10A.
G Yellow VSS high VSS input to speedometer. Connect to magnetic VSS or converted 4000 PPM signal from ECM. Note 3
H Brown VSS feed for ECM Feeds buffered VSS signal to ECM when a magnetic VSS is connected to speedometer. Note 3
J Pink TBI INJ1 Positive feed for injector. Hot in run, bulb test, or start. fused 5A
K Pink TBI INJ2 Positive feed for injector. Hot in run, bulb test, or start. fused 5A
L Tan/White Fuel pump Positive side of fuel pump, gets connected to the COM terminal of the fuel pump relay.
M Black VSSB ground Connect to ground
N Black A/C Power Positive feed for A/C compressor control relay contacts. Fused 25A
P Purple TCC Brake switch TCC brake. Hot in run, bulb test, or start only when brake pedal is NOT depressed.
R Purple VSS low VSS input to speedometer. Connect to magnetic VSS or to ground if using optical VSS and converter. Note 3
Notes
1. F is the switched power feed for the ECM, all switched 12 volt inputs on the ECM can be connected to this terminal. The constant 12 volt supply for the ECM comes from the rust colored fusible link with a single weatherpack disconnect at the terminal block near the battery.
2. J, & K are the positive feeds for the fuel injectors, One for each injector on TBI systems or one for each bank on PFI systems.
3. The Fiero speedometer system works differently than most other GM vehicles. Click HERE for more info.
Fiero C500 connector
I've found that the C500 connections vary considerably depending on year.
Pos. Wire color Circuit Description
A2 Black Ground Ground
A4 Yellow Start Hot in start, connect to gear selector switch. Automatic only
B3 Brown Charge Charge indicator light. Connect to alternator brown wire.
C1 Dark Blue Reverse Reverse light switch power feed. Connect to gear selector switch(auto.) or reverse switch(man.) Fused 10A. Note 1
C2 DkGreen/White(V6)
Tan(L4)
Temp gage Connect to temp sender, 1365ohm@100deg.,55ohm@260deg.
C3 White Tach Connect to coil or ign module.
D1 Dk Green/white Fan switch Connect to grounding fan switch or ECM fan output
D2 Lt Green/Black Fan switch Same as above(with optional two speed fan only)
D3 Dark Green Temp lamp Connect to grounding temp switch or ECM temp output.
E1 Lt Green Reverse Connect to gear selector switch(auto.) or reverse switch(man.) along with C1. Note 1
E2 Purple Start Hot in start, connect to starter. Manual only
E3 Pink Ignition Hot in run, bulb test, or start. Power feed for ignition coil
Cars equipped with four speed manual transaxle use a shifter mounted reverse switch. Cars with five speed use a transaxle mounted switch. '85 and newer cars are wired for both switches.
There is a stud terminal directly under the C500 for making all +12 volt constant connections.
The Fiero uses a separate module for cruise control. It is located behind the carpet on the drivers side inner kick panel. If you wish to use the new donor ECM to control the cruise control (recommended), you will need to extend the wires from the original module to the new ECM.
I didn't write this, but can't remember who did. .sorry.
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